You're So Dead (the perfect Instagram Influencer thriller!) by Ash Parsons (author)

The trust no-one tension of One of Us is Lying meets legendary scam Fyre Festival. A high-energy, wildly entertaining, read-in-one-sitting YA thriller to get obsessed with.
Plum Winter has always come in second to her sister, the unbelievably cool, famous influencer Peach Winter. And when Peach is invited to an all-expenses-paid trip to a luxurious art-and-music festival for influencers on a private island in the Caribbean, Plum decides it’s finally her time to shine. So she intercepts the invite – and asks her two best friends to come along to the fest with her. It’ll be a spring break they’ll never forget.
But the island is run-down, creepy, and there doesn’t even seem to be a festival – it’s just seven other quasi-celebrities and influencers, and none of the glitz and glamour she expected. Then people start to die… Plum and her friends soon realize that someone has lured each of them to the “festival” to kill them. Someone has a vendetta against every person on the island – and no one is supposed to leave alive.